Are there guidelines from BWF as to the variations between differing shuttle speed flights. is there a guideline for instance that says at at given atmospheric pressure, hall temperature, etc and force of racket hit, snglr of stroke etc that a, say speed 3 yonex shuttle, should fly, or perhaps given equality in conditions how much further one brand speed should fly than anothet speed of the same brand. I would assume not. I know that shuttles fly diffently under different atmosperic conditions and with the way they are hit but has this ever been assessed before under controlled conditions. I will probably look at this post in an hour or two and think to myself....what a stupid thing to ask...but what the hell
BWF does not manage shuttle-producing companies, why should they? As long as the shuttle flies according to the regulations (§3.1 of the laws) on tournament day in the tournament hall, it's good. The shuttle manufacturers themselves and third parties may issue guidelines. This is not a problem: You roughly know what speed you need in a given location (if you don't, just buy a tube of every speed and test, or ask anyone who has played there before). At large tournaments, multiple shuttle speeds are available, so you can just test all speeds at morning (or noon) and pick the best one.
I am aware that BWF doesnt manage shuttle producers and that at shuttle speeds are tested at start of play each day at events. however you have managed to hit the nail on the head with your comment (if you don't, just buy a tube of every speed and test. The reason I raised the issue was simply to try to ascertain if somebody had already done this and if the results were available so that clubs could have the facts if they were thinking of changing shuttle typs because of speed issues.